The present invention relates to a coupling device between a metal wave guide, a dielectric wave guide and an active semiconductor component which processes the ultra high frequency signal detected and outputs an electric signal over a microstrip line.
With this coupling device it is possible to pass from an electric signal at a very high frequency such as 94 GHz, conveyed by metal wave guides to a signal of lower frequency of the order of 1 GHz for example, which can be conveyed and processed with electronic semiconductor components such as transistors and integrated circuits. It provides integration of the electronic signal processing functions. The invention also relates to a simple mixer having a dielectric guide structure with isolated image, using Schottky diodes called Beam lead diodes.
It is known that 94 GHz corresponds to a window in which the ultrahigh frequency waves are transmitted particularily well through the earth's atmosphere and this frequency is very widely used for radar transmissions and detection.
Passing over from a device such as a metal wave guide to a device such as an electronic circuit on a substrate, supporting one or more active components--diodes, transistors, integrated circuits--even at the level of elementary ultra high frequency functions raises a certain number of problems. The development of active functions with dielectric guides is more difficult than that of passive functions. This is mainly due to the fact that the dielectric guide is an open structure: any discontinuity introduced by implanting a semiconductor component causes a parasite radiation and consequently the impedance seen by the component is formed of three components, a resistive part due to the radiation, a resistive part due to the useful load and a reactive part. Moreover, the direct integration of a semiconductor component in the dielectric guide is a difficult approach for it may cause the appearance of a higher order propagation mode or of a mode radiating the ultra high frequency wave transmitted by the metal wave guide.
Known constructions do not really provide integration of a component in a dielectric guide, in that the diodes are very often mounted in a chip or require an antenna for outputting the wave guide signal.